This invention relates generally to releasable and reseatable electrical connections within boreholes, and more particularly to the connection of a wireline to a tool interface.
Wirelines having an inner electrical conductor, a coaxial insulation layer, and an outer, protective wire covering, are in common usage in boreholes for connecting subsurface electrical equipment, for example, survey or steering tools, to surface electrical equipment. Such wirelines are generally routed from the wireline reel of the surface unit through a pulley or sheave at the upper level of a drilling rig, and may enter the drill string at the upper end, either through the rotary swivel, or other circulating head connections, down to the subsurface tool.
While drilling a borehole, it becomes necessary to add drill pipe sections to the drill string. In order to achieve this, any wireline within the drill string must be withdrawn to facilitate the addition or subtraction of the drill string elements. Withdrawal of the wireline and the attached tool may not be economical or easily achievable, especially in the case of very deep or highly deviated wells. The problems are further magnified in traversing the tool and wireline back into a highly deviated borehole, and effecting a reliable oriented seat at the bottom.
Furthermore, it often becomes necessary to have a combination of motor or slide drilling, and rotary drilling, in order to drill a directionally controlled well path. For these reasons, it is highly desirable to disconnect the upper section of the wireline so that it may be withdrawn only a short distance, while leaving the subsurface tool and a length of wireline in the borehole during the addition of drill pipe sections.